Add a assertJSONEqualsFixture helper to reduce boilerplate

Should not change (test) behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

internal/image/common_test.go

@@ -0,0 +1,29 @@
+package image
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// assertJSONEqualsFixture tests that jsonBytes is structurally equal to fixture,
+// possibly ignoring ignoreFields
+func assertJSONEqualsFixture(t *testing.T, jsonBytes []byte, fixture string, ignoreFields ...string) {
+	var contents map[string]any
+	err := json.Unmarshal(jsonBytes, &contents)
+	require.NoError(t, err)
+
+	fixtureBytes, err := os.ReadFile(filepath.Join("fixtures", fixture))
+	require.NoError(t, err)
+	var fixtureContents map[string]any
+
+	for _, f := range ignoreFields {
+		delete(contents, f)
+		delete(fixtureContents, f)
+	}
+	err = json.Unmarshal(fixtureBytes, &fixtureContents)
+	require.NoError(t, err)
+}

internal/image/docker_schema1_test.go

@@ -2,7 +2,6 @@ package image
 
 import (
 	"context"
-	"encoding/json"
 	"os"
 	"path/filepath"
 	"testing"
@@ -153,23 +152,11 @@ func TestManifestSchema1Serialize(t *testing.T) {
 	} {
 		serialized, err := m.serialize()
 		require.NoError(t, err)
-		var contents map[string]any
-		err = json.Unmarshal(serialized, &contents)
-		require.NoError(t, err)
-
-		original, err := os.ReadFile("fixtures/schema1.json")
-		require.NoError(t, err)
-		var originalContents map[string]any
-		err = json.Unmarshal(original, &originalContents)
-		require.NoError(t, err)
-
 		// Drop the signature which is generated by AddDummyV2S1Signature
-		delete(contents, "signatures")
-		delete(originalContents, "signatures")
 		// We would ideally like to compare “serialized” with some transformation of
-		// “original”, but the ordering of fields in JSON maps is undefined, so this is
+		// the original fixture, but the ordering of fields in JSON maps is undefined, so this is
 		// easier.
-		assert.Equal(t, originalContents, contents)
+		assertJSONEqualsFixture(t, serialized, "schema1.json", "signatures")
 	}
 }
 
@@ -462,30 +449,12 @@ func TestManifestSchema1ConvertToSchema2(t *testing.T) {
 	convertedJSON, mt, err := res.Manifest(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, manifest.DockerV2Schema2MediaType, mt)
-
-	byHandJSON, err := os.ReadFile("fixtures/schema1-to-schema2.json")
-	require.NoError(t, err)
-	var converted, byHand map[string]any
-	err = json.Unmarshal(byHandJSON, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	delete(converted, "config") // We don’t want to hard-code a specific digest and size of the marshaled config here
-	delete(byHand, "config")
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	// Ignore "config": we don’t want to hard-code a specific digest and size of the marshaled config here.
+	assertJSONEqualsFixture(t, convertedJSON, "schema1-to-schema2.json", "config")
 
 	convertedConfig, err := res.ConfigBlob(context.Background())
 	require.NoError(t, err)
-
-	byHandConfig, err := os.ReadFile("fixtures/schema1-to-schema2-config.json")
-	require.NoError(t, err)
-	converted = map[string]any{}
-	byHand = map[string]any{}
-	err = json.Unmarshal(byHandConfig, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedConfig, &converted)
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	assertJSONEqualsFixture(t, convertedConfig, "schema1-to-schema2-config.json")
 
 	// Conversion to schema2 together with changing LayerInfos works as expected (which requires
 	// handling schema1 throwaway layers):
@@ -555,30 +524,12 @@ func TestManifestSchema1ConvertToManifestOCI1(t *testing.T) {
 	convertedJSON, mt, err := res.Manifest(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, imgspecv1.MediaTypeImageManifest, mt)
-
-	byHandJSON, err := os.ReadFile("fixtures/schema1-to-oci1.json")
-	require.NoError(t, err)
-	var converted, byHand map[string]any
-	err = json.Unmarshal(byHandJSON, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	delete(converted, "config") // We don’t want to hard-code a specific digest and size of the marshaled config here
-	delete(byHand, "config")
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	// Ignore "config": we don’t want to hard-code a specific digest and size of the marshaled config here.
+	assertJSONEqualsFixture(t, convertedJSON, "schema1-to-oci1.json", "config")
 
 	convertedConfig, err := res.ConfigBlob(context.Background())
 	require.NoError(t, err)
-
-	byHandConfig, err := os.ReadFile("fixtures/schema1-to-oci1-config.json")
-	require.NoError(t, err)
-	converted = map[string]any{}
-	byHand = map[string]any{}
-	err = json.Unmarshal(byHandConfig, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedConfig, &converted)
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	assertJSONEqualsFixture(t, convertedConfig, "schema1-to-oci1-config.json")
 
 	// Conversion to OCI together with changing LayerInfos works as expected (which requires
 	// handling schema1 throwaway layers):

internal/image/docker_schema2_test.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"context"
 	"encoding/hex"
-	"encoding/json"
 	"errors"
 	"io"
 	"os"
@@ -92,20 +91,10 @@ func TestManifestSchema2Serialize(t *testing.T) {
 	} {
 		serialized, err := m.serialize()
 		require.NoError(t, err)
-		var contents map[string]any
-		err = json.Unmarshal(serialized, &contents)
-		require.NoError(t, err)
-
-		original, err := os.ReadFile("fixtures/schema2.json")
-		require.NoError(t, err)
-		var originalContents map[string]any
-		err = json.Unmarshal(original, &originalContents)
-		require.NoError(t, err)
-
 		// We would ideally like to compare “serialized” with some transformation of
-		// “original”, but the ordering of fields in JSON maps is undefined, so this is
+		// the original fixture, but the ordering of fields in JSON maps is undefined, so this is
 		// easier.
-		assert.Equal(t, originalContents, contents)
+		assertJSONEqualsFixture(t, serialized, "schema2.json")
 	}
 }
 
@@ -520,15 +509,7 @@ func TestConvertToManifestOCI(t *testing.T) {
 	convertedJSON, mt, err := res.Manifest(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, imgspecv1.MediaTypeImageManifest, mt)
-
-	byHandJSON, err := os.ReadFile("fixtures/schema2-to-oci1.json")
-	require.NoError(t, err)
-	var converted, byHand map[string]any
-	err = json.Unmarshal(byHandJSON, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	assertJSONEqualsFixture(t, convertedJSON, "schema2-to-oci1.json")
 }
 
 func TestConvertToManifestOCIAllMediaTypes(t *testing.T) {
@@ -541,15 +522,7 @@ func TestConvertToManifestOCIAllMediaTypes(t *testing.T) {
 	convertedJSON, mt, err := res.Manifest(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, imgspecv1.MediaTypeImageManifest, mt)
-
-	byHandJSON, err := os.ReadFile("fixtures/schema2-all-media-types-to-oci1.json")
-	require.NoError(t, err)
-	var converted, byHand map[string]any
-	err = json.Unmarshal(byHandJSON, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	assertJSONEqualsFixture(t, convertedJSON, "schema2-all-media-types-to-oci1.json")
 }
 
 func TestConvertToOCIWithInvalidMIMEType(t *testing.T) {
@@ -573,19 +546,10 @@ func TestConvertToManifestSchema1(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, manifest.DockerV2Schema1SignedMediaType, mt)
 
-	// byDockerJSON is the result of asking the Docker Hub for a schema1 manifest,
+	// schema2-to-schema1-by-docker.json is the result of asking the Docker Hub for a schema1 manifest,
 	// except that we have replaced "name" to verify that the ref from
 	// memoryDest, not from originalSrc, is used.
-	byDockerJSON, err := os.ReadFile("fixtures/schema2-to-schema1-by-docker.json")
-	require.NoError(t, err)
-	var converted, byDocker map[string]any
-	err = json.Unmarshal(byDockerJSON, &byDocker)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	require.NoError(t, err)
-	delete(byDocker, "signatures")
-	delete(converted, "signatures")
-	assert.Equal(t, byDocker, converted)
+	assertJSONEqualsFixture(t, convertedJSON, "schema2-to-schema1-by-docker.json", "signatures")
 
 	assert.Equal(t, GzippedEmptyLayer, memoryDest.storedBlobs[GzippedEmptyLayerDigest])
 

internal/image/oci_test.go

@@ -94,20 +94,10 @@ func TestManifestOCI1Serialize(t *testing.T) {
 	} {
 		serialized, err := m.serialize()
 		require.NoError(t, err)
-		var contents map[string]any
-		err = json.Unmarshal(serialized, &contents)
-		require.NoError(t, err)
-
-		original, err := os.ReadFile("fixtures/oci1.json")
-		require.NoError(t, err)
-		var originalContents map[string]any
-		err = json.Unmarshal(original, &originalContents)
-		require.NoError(t, err)
-
 		// We would ideally like to compare “serialized” with some transformation of
-		// “original”, but the ordering of fields in JSON maps is undefined, so this is
+		// the original fixture, but the ordering of fields in JSON maps is undefined, so this is
 		// easier.
-		assert.Equal(t, originalContents, contents)
+		assertJSONEqualsFixture(t, serialized, "oci1.json")
 	}
 }
 
@@ -456,17 +446,7 @@ func TestManifestOCI1ConvertToManifestSchema1(t *testing.T) {
 	convertedJSON, mt, err := res.Manifest(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, manifest.DockerV2Schema1SignedMediaType, mt)
-
-	byHandJSON, err := os.ReadFile("fixtures/oci1-to-schema1.json")
-	require.NoError(t, err)
-	var converted, byHand map[string]any
-	err = json.Unmarshal(byHandJSON, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	require.NoError(t, err)
-	delete(byHand, "signatures")
-	delete(converted, "signatures")
-	assert.Equal(t, byHand, converted)
+	assertJSONEqualsFixture(t, convertedJSON, "oci1-to-schema1.json", "signatures")
 
 	assert.Equal(t, GzippedEmptyLayer, memoryDest.storedBlobs[GzippedEmptyLayerDigest])
 
@@ -517,6 +497,9 @@ func TestManifestOCI1ConvertToManifestSchema1(t *testing.T) {
 	var expected manifest.NonImageArtifactError
 	assert.ErrorAs(t, err, &expected)
 
+	// FIXME: Test that conversion of an encrypted image fails
+	// FIXME: Test that conversion with encryption fails
+
 	// FIXME? Test also the other failure cases, if only to see that we don't crash?
 }
 
@@ -531,15 +514,7 @@ func TestConvertToManifestSchema2(t *testing.T) {
 	convertedJSON, mt, err := res.Manifest(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, manifest.DockerV2Schema2MediaType, mt)
-
-	byHandJSON, err := os.ReadFile("fixtures/oci1-to-schema2.json")
-	require.NoError(t, err)
-	var converted, byHand map[string]any
-	err = json.Unmarshal(byHandJSON, &byHand)
-	require.NoError(t, err)
-	err = json.Unmarshal(convertedJSON, &converted)
-	require.NoError(t, err)
-	assert.Equal(t, byHand, converted)
+	assertJSONEqualsFixture(t, convertedJSON, "oci1-to-schema2.json")
 
 	// This can share originalSrc because the config digest is the same between oci1-artifact.json and oci1.json
 	artifact := manifestOCI1FromFixture(t, originalSrc, "oci1-artifact.json")
@@ -549,6 +524,9 @@ func TestConvertToManifestSchema2(t *testing.T) {
 	var expected manifest.NonImageArtifactError
 	assert.ErrorAs(t, err, &expected)
 
+	// FIXME: Test that conversion of an encrypted image fails
+	// FIXME: Test that conversion with encryption fails
+
 	// FIXME? Test also the other failure cases, if only to see that we don't crash?
 }